Distribution patterns of vegetation on the sand hills of north-central and northwestern Oklahoma are investigated in this study. Two relatively distinct physiognomic groups are encountered along the environmental gradient, deciduous forest to the east, and grass/shrub to the west. The boundary between these two groups corresponds with a change from sandy soils having higher organic matter content in the east to very sandy soil with little organic matter to the west. The objectives of this study are to describe the pattern of vegetational change, indentify distinct communities if they exist, and relate community boundaries to the environmental gradient.